Answer:
<h2>Demographic measures are the actual changes in size, composition and distribution due to changes in demographic components like birth, death and migration, as a result of their respective processes like rate of fertility, mortality and migration.</h2>
The warm-up period before a workout allows the persons muscles to stretch out, and work up to the more intense workout, without hurting, tearing, or injuring. It increases heart rate, which loosens up joints, and increases blood flow to muscles, all which prevents the person from getting hurt.
It is because the “building” word that denotes infrastructures is a gerund. Gerunds are nouns that came from verbs + a suffix “ing". So in this case, “building” comes from the verb “built" (which implies that something is already done building something) + the “-ing”.